why does google maps show country borders so poorly?

That’s true, except for a few countries where I presume Google has shied away from controversy. E.g. if you search for India (which has a dispute over Kashmir), Pakistan (Kashmir) and Israel (West Bank), the Google results do not show a neatly highlighted border.

Edit 1: other countries without Google highlighted borders: China, Japan (Diaoyu/Senkaku disputed islands?) and the Philippines (Spratly Islands?)

Since this thread has been resurrected, have a look at the “National Geographic” style basemap at ArcGIS Online. Or at Michelin’s online service.